Hand Flashcards
surface anatomy
palmar side digital/proximal/palmar interphalangial crease digital/proximal/thenar/wrist crease thenar eminence hypothenar eminence
dorsal side metacarpophalangeal joints (knuckles) extensor digitorum tendons 1st dosal interosseous m. anatomical snuff box (radial pulse)
total hand and wrist bones
27, not including sesamoid bones
ligaments of hand
piso-metacarpal ligament piso-hamate ligament palmar radiocarpal ligament dorsal radiocarpal ligament transverse carpal ligament (flexor retinaculum)
which hand/wrist joints are hinge joints?
interphalangeal joint
- motion in only one direction (flexion/extension)
which hand/wrist joints are condyloid joints?
MCP joints aD/aBduction flexion extension circumduction axial rotation (only in extended position)
which hand/wrist joints are saddle joints?
1st carpometacarpal joint
aD/aBduction
flexion/extension
opposition
NO axial rotation
arthrodial (sliding) joint
2nd-5th carpometacarpal joints
ganglion cyst (synovial cyst)
benign swelling above joints (usually near scaphoid/lunate joint - 80%)
painless
bc of outpocketing/herniation of synovial capsule at a weakened region
50% recurrence post aspiration/surgery
osteoarthritis
wear &tear disease women>men asymmetry cartilage/bone loss bony growths (Heberden's node, Bouchard's node) may or may not be painful
RA
AI disease women>men symmetrical joint pain ulnar deviation joint swelling (soft nodules)
boutonniere thumb deformity (PIP flexion, DIP extension)
difficulty making OK sign
anterior interosseous nerve damage
- Paresis of flexor digitorum profundus (lateral) and flexor pollicus longus.
- a pinch instead due to weakened flexion of interphalangeal joint of thumb and distal interphalangeal joint of index finger
fibrous and synovial digital sheaths
fibrous sheaths (cruciform and annular shapes)
digital synovial sheath
synovial sheath
- common synovial sheath (ulnar bursa)
- FPL sheath
Inability to protonate could be due to
medial n. damage
Outcrop muscles
APL
EPB
EPL
EI
extensor pollicis longus
pivots on dorsal radial (Lister’s) tubercle
central band
extends PIP
lateral band
extends DIP
unipennate lumbricals
1 and 2
bipennate lumbricals
3 and 4
boutonniere (“button hole’) deformity
via jamming finger, laceration, RA
CENTRAL band tears
lateral bands move ventral to PIP axis (via lumbrical/interosseous m. action)
relocated lateral bands –> hyperextend DIP and flex PIP as attempts are made to extend finger
mallet finger
ruptured extension tendon (where LATERAL bands insert onto distal phalanx)
intrinsic thumb muscles
abductor pollicis brevis
flexor pollicis brevis
opponens pollicis
aDductor pollicis
extrinsic thumb muscles
extensor pollicis longus
extensor pollicis brevis
aBductor pollicis longus
flexor pollicis longus
which thenar m. has superficial and deep heads? innervation?
flexor pollicis brevis
superficial head –> median nerve (recurrent branch)
deep head –> ulnar n.
superficial palmar arch of radial a. passes between which two thenar muscles?
opponens pollicis
aBductor pollicis brevis
deep palmar arch of radial a. passes through 2 heads of which thenar muscles?
through transverse and oblique heads of adductor pollicis
primary m. that flex the metacarpophalangeal joint
lumbricals
mallet finger
lateral band is avulsed from the distal phalanx
ulnar n. goes through ulnar tunnel and splits into …
deep (motor) branch of ulnar n.
superficial (mostly sensory, also supplies palmaris brevis)
if only recurrent branch of median n. damaged –>
thumb opposition lost
carpal tunnel syndrome: m. and skin affected
APB
FPB (superficial head only)
opponens pollicis
1st and 2rd lumbricals
lateral 3.5 digits (palmar side)
lateral, distal ends of 3.5 digits (dorsal side)
persistent median a.
(5-10% prevalence)
norm regresses during fetal life
recognized cause of carpal tunnel syndrome (usu due to thrombosed MA, anticoagulant therapy often clears sx)
often assoc w/ bifurcated median n.
ulnar (guyon’s) tunnel syndrome
compression of ulnar n. in ulnar canal (focal damage to myelin sheath: neuropraxia)
MOI: pressure on ulnar canal (extended cycling)
m. affected: all intrinsic hand m. EXCEPT 4.5 innervated by median n.
deficits
- opposition (weak ODM)
- pinching (weak adductor pollicis)
- loss of fine motor control
skin affecetd
- medial 1.5 fingers
- paresthesia, pain
- temporary recovery may be slow
